What you're describing is insurance misrepresentation fraud. You have to answer insurance questions truthfully. When they ask you who will be operating the vehicle the majority of the time, the answer would be you (and not your brother or father). The premium is based on the person who uses the vehicle the majority of the time, and not the person who owns it.
Penalties if caught? Well, both you and your brother/father would probably be unable to drive for a number of years because insurance would be prohibitively expensive. The insurer could deny coverage in the event of a collision. etc.
Your insurer has ways of catching you in your fraud and actually employ and contract private investigators in their Special Investigations Unit for this sort of thing. As Platinum_Cycle pointed out, this question comes up a lot in the forum and is an SIU textbook case of insurance fraud. You aren't the first under-25yo genius to dream up such a scam
It's actually fun to sometimes read the SIU files over lunch hour for a few laughs over what some people thought they could get away with.